Tacrine (1,2,3,4-tetrahydro-9-aminoacridine, monohydrochloride monohydrate, CI-970 is a potent, centrally active, reversible cholinesterase inhibitor. This center is one of 18 nationwide using tacrine in a double-blind, placebo controlled study to test the efficacy of this drug in senile dementia of the Alzheimer's type. The multi-center trial was begun as a result of flavorable results with a small number of patients using tacrine published in the fall of 1986.